Wireless power transmitter, wireless power receiver and control method thereof

ABSTRACT

A control method for performing wireless charging in a wireless power receiver is disclosed. The control method includes receiving charging power from a wireless power transmitter; detecting transition of the wireless power receiver from a Stand Alone (SA) mode to a Non Stand Alone (NSA) mode; upon detecting the mode transition, generating a message including address information used to re-connect with the wireless power transmitter; and transmitting the message to the wireless power transmitter.

PRIORITY

This application claims priority under 35 U.S.C. §119(a) to a KoreanPatent Application filed in the Korean Intellectual Property Office onMay 3, 2013 and assigned Serial No. 10-2013-0050293, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND

1. Field of Invention

The present invention generally relates to a wireless power transmitter,a wireless power receiver and a control method thereof, and moreparticularly, to a wireless power transmitter capable of wirelesslytransmitting charging power, a wireless power receiver capable ofwirelessly receiving charging power, and a control method thereof

2. Description of the Related Art

Mobile terminals such as cellular phones and Personal Digital Assistants(PDAs) are powered by a rechargeable battery due to their portability.In order to charge the battery, electrical energy may be supplied to thebattery of the mobile terminal using a separate charging device.Typically, the charging device and the battery have separate contactterminals mounted on their exposed surfaces, and the charging device andthe battery may be electrically connected by causing their contactterminals to be in contact with each other.

However, this contact type charging scheme is subject to contaminationdue to foreign matter since the contact terminals are exposed to theoutside, so the battery charging may not be correctly performed. Thebattery also may not be correctly charged when the contact terminals areexposed to moisture.

In order to solve these and other problems, wireless or non-contactcharging technology has recently been developed and utilized in manyelectronic devices.

The wireless charging technology, which is based on wireless powertransmission/reception, may ensure a system in which a battery may beautomatically charged by simply placing, for example, a cellular phoneon a charging pad without connecting the cellular phone to a separatecharging connector. Typically, wireless electronic toothbrushes orcordless electric shavers are well known as devices employing wirelesscharging technology. The wireless charging technology may improve thewaterproof performance of electronic products by wirelessly charging theelectronic products, and may ensure the portability of electronicdevices because of the unnecessity of a wired charger. In the coming eraof electric vehicles, the related technologies are expected tosignificantly evolve.

The wireless charging technology may be roughly classified into acoil-based electromagnetic induction scheme, a resonance scheme, andRadio Frequency (RF)/micro wave radiation scheme that convertselectrical energy into microwaves and transfers the microwaves.

Up to now, the electromagnetic induction scheme has been widely used.However, as experiments of wirelessly transmitting power from a distanceof tens of meters using microwaves have been recently successful at homeand abroad, it seems that all electronic products may be wirelesslycharged without wires anytime anyplace in the near future.

The electromagnetic induction-based power transmission methodcorresponds to a scheme of transmitting power between a primary coil anda secondary coil. If a magnet moves around a coil, an induced currentmay be generated. Based on this principle, a transmitter generates amagnetic field, and a current is induced in a receiver due to a changein the magnetic field, creating energy. This phenomenon is called anelectromagnetic induction phenomenon, and a power transmission methodemploying this phenomenon is excellent in energy transmissionefficiency.

As for the resonance scheme, electricity is wirelessly transferred byusing the resonance-based power transmission principle as a coupled modetheory even if an electronic device is apart from a charging device byseveral meters. The wireless charging system causes electromagneticwaves containing electrical energy to resonate, and the resonatingelectrical energy may be directly transferred only to an electronicdevice having the resonant frequency. The unused electrical energy maybe reabsorbed as an electromagnetic field instead of spreading in theair, so the resonating electrical energy, unlike other electromagneticwaves, may not affect the nearby devices or human bodies.

Although research has recently been conducted on the wireless chargingscheme, no standards have been proposed for wireless charging priority,search for a wireless power transmitter and a wireless power receiver,selection of a frequency for communication between a wireless powertransmitter and a wireless power receiver, adjustment of wireless power,selection of a matching circuit, distribution of communication time foreach wireless power receiver in one charging cycle, and the like. Inparticular, there is a need for a standard for the configuration andprocedure in which a wireless power receiver selects a wireless powertransmitter from which the wireless power receiver will receive wirelesspower.

In particular, there is a need to develop a method in which duringdischarge of its battery, a wireless power receiver may performcommunication with a wireless power transmitter by receiving chargingpower from the wireless power transmitter. The wireless power receivermay store a stack for communication in its Application Processor (AP),and may load the stack from the AP and communicate with the wirelesspower transmitter in a process of performing communication with thewireless power transmitter.

However, if its battery is discharged, the wireless power receiver maynot load the stack from the AP, so communication for wireless chargingmay not be performed.

SUMMARY

The present invention has been made to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below.

Accordingly, an aspect of the present invention is to provide a wirelesspower receiver capable of performing communication with a wireless powertransmitter even during discharge of its battery, and a control methodthereof.

Another aspect of the present invention is to provide a wireless powertransmitter for performing communication in response to the batterydischarge, and a control method thereof.

In accordance with an aspect of the present invention, there is provideda control method for performing wireless charging in a wireless powerreceiver. The control method includes receiving charging power from awireless power transmitter; detecting transition of the wireless powerreceiver from a Stand Alone (SA) mode to a Non Stand Alone (NSA) mode;upon detecting the mode transition, generating a message includingaddress information used to re-connect with the wireless powertransmitter; and transmitting the message to the wireless powertransmitter.

In accordance with another aspect of the present invention, there isprovided a control method for performing wireless charging in a wirelesspower transmitter. The control method includes transmitting chargingpower to a wireless power receiver; receiving, from the wireless powerreceiver, a message including address information used to re-connectwith the wireless power transmitter; and upon receiving the message fromthe wireless power receiver, reconnecting with the wireless powerreceiver using the address information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates the concept of the overall operation of a wirelesscharging system;

FIG. 2 is a block diagram of a wireless power transmitter and a wirelesspower receiver according to an embodiment of the present invention;

FIG. 3 is a detailed block diagram of a wireless power transmitter and awireless power receiver according to an embodiment of the presentinvention;

FIG. 4 is a flow diagram illustrating operations of a wireless powertransmitter and a wireless power receiver according to an embodiment ofthe present invention;

FIG. 5 is a flowchart illustrating operations of a wireless powertransmitter and a wireless power receiver according to anotherembodiment of the present invention;

FIG. 6 is a time axis graph for power applied by a wireless powertransmitter;

FIG. 7 is a flowchart illustrating a control method of a wireless powertransmitter according to an embodiment of the present invention;

FIG. 8 is a time axis graph for power applied by a wireless powertransmitter in an embodiment of FIG. 7;

FIG. 9 is a flowchart illustrating a control method of a wireless powertransmitter according to an embodiment of the present invention;

FIG. 10 is a time axis graph for power applied by a wireless powertransmitter in an embodiment of FIG. 9;

FIG. 11 is a block diagram of a wireless power transmitter and awireless power receiver according to an embodiment of the presentinvention;

FIG. 12A is a flowchart illustrating a control method of a wirelesspower receiver according to an embodiment of the present invention;

FIG. 12B is a flowchart illustrating a control method of a wirelesspower transmitter according to an embodiment of the present invention;

FIG. 13 is a flowchart illustrating operations of a wireless powertransmitter and a wireless power receiver according to an embodiment ofthe present invention;

FIG. 14 is a block diagram of a communication unit and peripheralcomponents of a wireless power receiver according to an embodiment ofthe present invention;

FIG. 15A is a flowchart illustrating a control method of a wirelesspower receiver according to an embodiment of the present invention;

FIG. 15B is a flowchart illustrating a control method of a wirelesspower receiver according to an embodiment of the present invention;

FIG. 15C is a flowchart illustrating a control method of a wirelesspower transmitter according to an embodiment of the present invention;and

FIG. 16 is a block diagram of a wireless power receiver according to anembodiment of the present invention.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of embodiments ofthe present invention as defined by the claims and their equivalents. Itincludes various specific details to assist in that understanding butthese are to be regarded as merely examples. Accordingly, those ofordinary skilled in the art will recognize that various changes andmodifications of the embodiments described herein can be made withoutdeparting from the scope and spirit of the present invention. Inaddition, descriptions of well-known functions and constructions may beomitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to their dictionary meanings, but are merely used to enable aclear and consistent understanding of the present invention.Accordingly, it should be apparent to those skilled in the art that thefollowing description of embodiments of the present invention isprovided for illustration purposes only and not for the purpose oflimiting the disclosure as defined by the appended claims and theirequivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

By the term “substantially”, it is meant that the recitedcharacteristic, parameter, or value need not be achieved exactly, butthat deviations or variations, including for example, tolerances,measurement error, measurement accuracy limitations and other factorsknown to those of skill in the art, may occur in amounts that do notpreclude the effect the characteristic was intended to provide.

FIG. 1 illustrates the concept of the overall operation of a wirelesscharging system. As illustrated in FIG. 1, the wireless charging systemincludes, a wireless power transmitter 100 and at least one wirelesspower receivers 110-1, 110-2 and 110-n.

The wireless power transmitter 100 wirelessly transmits power 1-1, 1-2and 1-n to the wireless power receivers 110-1, 110-2 and 110-n,respectively. More specifically, the wireless power transmitter 100wirelessly transmits the power 1-1, 1-2 and 1-n only to the wirelesspower receiver(s) that is authenticated by performing a predeterminedauthentication procedure.

The wireless power transmitter 100 forms an electrical connection to thewireless power receivers 110-1, 110-2 and 110-n. For example, thewireless power transmitter 100 may transmit wireless power in the formof electromagnetic wave to the wireless power receivers 110-1, 110-2 and110-n.

The wireless power transmitter 100 may perform bi-directionalcommunication with the wireless power receivers 110-1, 110-2 and 110-n.The wireless power transmitter 100 and the wireless power receivers110-1, 110-2 and 110-n process or transmit/receive packets 2-1, 2-2 and2-n, which are configured in a predetermined frame. The frame will bedescribed in detail below. The wireless power receiver may beimplemented as, for example, a mobile communication terminal, a PersonalDigital Assistants (PDA), a Personal Multimedia Player (PMP), a smartphone, and the like.

The wireless power transmitter 100 wirelessly supplies power to theplurality of wireless power receivers 110-1, 110-2 and 110-n. Forexample, the wireless power transmitter 100 may transmit power to theplurality of wireless power receivers 110-1, 110-2 and 110-n using theresonance scheme. If the wireless power transmitter 100 adopts theresonance scheme, the distance between the wireless power transmitter100 and the plurality of wireless power receivers 110-1, 110-2 and 110-nshould be less than 30 m. If the wireless power transmitter 100 adoptsthe electromagnetic induction scheme, the distance between the wirelesspower transmitter 100 and the plurality of wireless power receivers110-1, 110-2 and 110-n should be preferably less than 10 cm.

The wireless power receivers 110-1, 110-2 and 110-n receive wirelesspower from the wireless power transmitter 100, and charge batteriesmounted therein with the received power. The wireless power receivers110-1, 110-2 and 110-n may transmit, to the wireless power transmitter100, a signal for requesting transmission of wireless power, informationneeded for reception of wireless power, status information of thewireless power receiver, information for control of the wireless powertransmitter 100, and the like. The transmission signal information willbe described in detail below.

The wireless power receivers 110-1, 110-2 and 110-n may send a messageindicating their charging status to the wireless power transmitter 100.

The wireless power transmitter 100 may include a display means such as adisplay, and displays the status of each of the wireless power receivers110-1, 110-2 and 110-n on the display based on a message received fromeach of the wireless power receivers 110-1, 110-2 and 110-n. Inaddition, the wireless power transmitter 100 may display, on thedisplay, the time that is expected until each of the wireless powerreceivers 110-1, 110-2 and 110-n is fully charged.

The wireless power transmitter 100 may transmit a control signal fordisabling the wireless charging function to each of the wireless powerreceivers 110-1, 110-2 and 110-n. Upon receiving the control signal fordisabling the wireless charging function from the wireless powertransmitter 100, the wireless power receiver disables the wirelesscharging function.

FIG. 2 is a block diagram of a wireless power transmitter and a wirelesspower receiver according to an embodiment of the present invention.

As illustrated in FIG. 1, a wireless power transmitter 200 includes apower transmitting unit 211, a controller 212, and a communication unit213. A wireless power receiver 250 may include a power receiving unit251, a controller 252 and a communication unit 253.

The power transmitting unit 211 supplies the power required by thewireless power transmitter 200, and may wirelessly supply the power tothe wireless power receiver 250. The power transmitting unit 211supplies power in the form of an Alternating Current (AC) waveform, ormay supply power in the form of Direct Current (DC) waveform. In thelatter case, the power transmitting unit 211 converts the DC waveforminto an AC waveform using an inverter, and supplies the power in theform of an AC waveform. The power transmitting unit 211 may beimplemented in the form of built-in battery, or may be implemented inthe form of power receiving interface to receive power from the outsideand supply the received power to the other components. It will beapparent to those of ordinary skill in the art that any means mayreplace the power transmitting unit 211 as long as it can supply powerin the form of a predetermined AC waveform.

In addition, the power transmitting unit 211 may provide AC waveforms tothe wireless power receiver 250 in the form of electromagnetic waves.The power transmitting unit 211 may further include a resonance circuit,so the power transmitting unit 211 transmits or receives predeterminedelectromagnetic waves. If the power transmitting unit 211 is implementedwith a resonance circuit, an inductance L of a loop coil in theresonance circuit may be subject to change. It will be apparent to thoseof ordinary skill in the art that any means may replace the powertransmitting unit 211 as long as it can transmit and receiveelectromagnetic waves.

The controller 212 controls the overall operation of the wireless powertransmitter 200. The controller 212 may control the overall operation ofthe wireless power transmitter 200 using an algorithm, a program or anapplication, each of which is read from a storage (not shown) andrequired for the control. The controller 212 may be implemented in theform of a Central Processing Unit (CPU), a microprocessor, aminicomputer, and the like. A detailed operation of the controller 212will be described in more detail below.

The communication unit 213 performs communication with the wirelesspower receiver 250 using a predetermined communication scheme. Thecommunication unit 213 may perform communication with the communicationunit 253 of the wireless power receiver 250, using Near FieldCommunication (NFC), Zigbee, Infrared Data Association (IrDA), VisibleLight Communication (VLC), Bluetooth, Bluetooth Low Energy (BLE), andthe like. The communication unit 213 may employ a Carrier Sense MultipleAccess with Collision Avoidance (CSMA/CA) algorithm. The abovecommunication schemes are merely illustrative, and the scope of thepresent invention will not limited to a specific communication schemeperformed in the communication unit 213.

The communication unit 213 transmits a signal for information about thewireless power transmitter 200. The communication unit 213 may unicast,multicast, or broadcast the signal. Table 1 below illustrates a datastructure of a signal transmitted from the wireless power transmitter200 according to an embodiment of the present invention. The wirelesspower transmitter 200 transmits a signal having the following frame at apreset cycle, and the signal may be called herein a ‘Notice’ signal.

TABLE 1 RX to net- Report frame protocol sequence work (schedule Numbertype version number ID mask) Reserved of Rx Notice 4 bit 1 Byte 1 Byte 1Byte 5 bit 3 bit

In Table 1, a ‘frame type’ field, which is a field indicating a type ofthe signal, indicates that the signal is a ‘Notice’ signal. A ‘protocolversion’ field, which is a field indicating a protocol type of acommunication scheme, may be allocated, for example, 4 bits. A ‘sequencenumber’ field, which is a field indicating a sequence number of thesignal, may be allocated, for example, 1 byte. The sequence number mayincrease one by one in response to, for example, a signaltransmission/reception phase. A ‘network ID’ field, which is a fieldindicating a network ID of the wireless power transmitter 200, may beallocated, for example, 1 byte. A ‘Rx to Report (schedule mask)’ field,which is a field indicating the wireless power receivers that will makea report to the wireless power transmitter 200, may be allocated, forexample, 1 byte. Table 2 below illustrates the ‘Rx to Report (schedulemask)’ field according to an embodiment of the present invention.

TABLE 2 Rx to Report(schedule mask) Rx1 Rx2 Rx3 Rx4 Rx5 Rx6 Rx7 Rx8 1 00 0 0 1 1 1

In Table 2, Rx1 to Rx8 may correspond to first to eighth wireless powerreceivers. The ‘Rx to Report (schedule mask)’ field may be implementedto cause a wireless power receiver with a schedule mask number=1 to makea report.

In Table 1, a ‘Reserved’ field, which is a field reserved for futureuse, may be allocated, for example, 5 bits. A ‘Number of Rx’ field,which is a field indicating the number of wireless power receiversaround the wireless power transmitter 200, may be allocated, forexample, 3 bits.

The communication unit 213 receives power information from the wirelesspower receiver 250. The power information includes at least one of thecapacity, battery level, the number of chargings (i.e., charging timesof a battery), usage, battery capacity and battery percentage of thewireless power receiver 250. The communication unit 213 transmits acharging function control signal for controlling the charging functionof the wireless power receiver 250. The charging function control signalmay be a control signal for enabling or disabling the charging functionby controlling the power receiving unit 251 of the wireless powerreceiver 250. More specifically, the power information may includeinformation about insertion of a wired charging terminal, transitionfrom a Stand Alone (SA) mode to a Non Stand Alone (NSA) mode, andrelease of error situations, all of which will be described below.

The communication unit 213 may receive not only the signal from thewireless power receiver 250, but also the signal from at least one otherwireless power transmitter (not shown). For example, the communicationunit 213 may receive the ‘Notice’ signal of the frame in Table 1 fromanother wireless power transmitter.

Although the power transmitting unit 211 and the communication unit 213are configured as different hardware structures in FIG. 2, so thewireless power transmitter 200 seems to communicate in an out-band way,this is merely illustrative. In the present invention, the powertransmitting unit 211 and the communication unit 213 may be implementedas a single hardware structure, so the wireless power transmitter 200may perform communication in an in-band way.

The wireless power transmitter 200 transmits and receives a variety ofsignals to/from the wireless power receiver 250. Accordingly, a processin which the wireless power receiver 250 joins the wireless powernetwork managed by the wireless power transmitter 200 and a process inwhich the wireless power receiver 250 is charged through wireless powertransmission/reception are performed, and a detailed description thereofwill be given below.

FIG. 3 is a detailed block diagram of a wireless power transmitter and awireless power receiver according to an embodiment of the presentinvention.

As illustrated in FIG. 3, the wireless power transmitter (or PowerTransmission Unit (PTU)) 200 includes the power transmitting unit 211, acontroller/communication unit (or MCU & Out-of-band Signaling unit)212/213, a driver 214, an amplifier 215, and a matcher 216. The wirelesspower receiver (or Power Reception Unit (PRU)) 250 includes the powerreceiving unit 251, a controller/communication unit (or MCU &Out-of-band Signaling unit) 252/253, a rectifier 254, a DC/DC converter255, a switch 256, and a load unit 257.

The driver 214 outputs DC power having a preset voltage value. Thevoltage value of the DC power output from the driver 214 is controlledby the controller/communication unit 212/213.

A DC current output from the driver 214 is output to the amplifier 215.The amplifier 215 amplifies the DC current with a preset gain. Inaddition, the amplifier 215 converts the DC current into an AC currentbased on the signal received from the controller/communication unit212/213. Accordingly, the amplifier 215 outputs an AC current.

The matcher 216 performs impedance matching. For example, the matcher216 adjusts the impedance seen from the matcher 216 to control theoutput power to have high efficiency and high power. The matcher 216adjusts the impedance under controller of the controller/communicationunit 212/213. The matcher 216 may include at least one of a coil and acapacitor. The controller/communication unit 212/213 may control aconnection status to at least one of the coil and the capacitor, andperforms impedance matching according thereto.

The power transmitting unit 211 transmits the input AC power to thepower receiving unit 251. Each of the power transmitting unit 211 andthe power receiving unit 251 may be implemented with a resonance circuithaving the same resonant frequency. For example, the resonant frequencymay be determined as 6.78 MHz.

The controller/communication unit 212/213 performs communication withthe controller/communication unit 252/253 in the wireless power receiver250, and may perform, for example, bi-directional communication at afrequency of 2.4 GHz.

The power receiving unit 251 receives charging power.

The rectifier 254 rectifies the wireless power received at the powerreceiving unit 251 into DC power, and may be implemented in the form of,for example, a bridge diode. The DC/DC converter 255 converts therectified power with a preset gain. For example, the DC/DC converter 255may convert the rectified power so that its output terminal 259 may havea voltage of 5V. The minimum value and maximum value of a voltageapplicable to a front end 258 of the DC/DC converter 255 may be set inadvance.

The switch 256 connects the DC/DC converter 255 to the load unit 257.The switch 256 keeps an ON/OFF status under control of the controller252. If the switch 256 is in an ON status, the load unit 257 stores theconverted power received from the DC/DC converter 255.

FIG. 4 is a flow diagram illustrating operations of a wireless powertransmitter and a wireless power receiver according to an embodiment ofthe present invention.

As illustrated in FIG. 4, a wireless power transmitter (or PTU) 400 ispowered up in step S401. Upon power up, the wireless power transmitter400 configures (or sets) the environment in step S402.

The wireless power transmitter 400 enters a power save mode in stepS403. In the power save mode, the wireless power transmitter 400 mayapply different detection-purpose power beacons at their own cycles, anda detailed description thereof will be given with reference to FIG. 6.For example, as in FIG. 4, the wireless power transmitter 400 may applydetection-purpose power beacons 404 and 405, and the detection-purposepower beacons 404 and 405 may be different from each other in magnitudeof a power value. All or some of the detection-purpose power beacons 404and 405 may have the power that can drive a communication unit of awireless power receiver (or PRU) 450. For example, the wireless powerreceiver 450 performs communication with the wireless power transmitter400 by driving its communication unit by means of all or some of thedetection-purpose power beacons 404 and 405. The above status isreferred to as a null status S406.

The wireless power transmitter 400 may detect a change in load, which iscaused by the arrangement of the wireless power receiver 450. Thewireless power transmitter 400 enters a low power mode in step S408. Thelow power mode will be described in detail with reference to FIG. 6. Thewireless power receiver 450 drives its communication unit based on thepower received from the wireless power transmitter 400 in step S409.

The wireless power receiver 450 transmits a PTU searching signal to thewireless power transmitter 400 in step S410. The wireless power receiver450 transmits the PTU searching signal as an Advertisement signal thatis based on Bluetooth Low Energy (BLE). The wireless power receiver 450may periodically transmit the PTU searching signal and receive aresponse signal from the wireless power transmitter 400, or may transmitthe PTU searching signal until a preset time has arrived.

Upon receiving the PTU searching signal from the wireless power receiver450, the wireless power transmitter 400 transmits a PRU Response signalin step S411. The response signal may be used to form a connectionbetween the wireless power transmitter 400 and the wireless powerreceiver 450.

The wireless power receiver 450 transmits a PRU static signal in stepS412. The PRU static signal may be a signal indicating a status of thewireless power receiver 450, and may be used to request joining thewireless power network managed by the wireless power transmitter 400.

The wireless power transmitter 400 transmits a PTU static signal in stepS413. The PTU static signal transmitted by the wireless powertransmitter 400 may be a signal indicating the capability of thewireless power transmitter 400.

If the wireless power transmitter 400 and the wireless power receiver450 exchange the PRU static signal and the PTU static signal with eachother, the wireless power receiver 450 periodically transmits a PRUDynamic signal in steps S414 and S415. The PRU Dynamic signal mayinclude information about at least one parameter measured in thewireless power receiver 450. For example, the PRU Dynamic signal mayinclude information about a voltage at a rear end of a rectifier in thewireless power receiver 450. The above status of the wireless powerreceiver 450 is referred to as a boot status S407.

The wireless power transmitter 400 enters a power transfer mode in stepS416, and the wireless power transmitter 400 transmits a PRU commandsignal, which is a command signal for enabling the wireless powerreceiver 450 to perform charging, in step S417. In the power transfermode, the wireless power transmitter 400 transmits charging power.

The PRU command signal transmitted by the wireless power transmitter 400may include information for enabling/disabling the charging of thewireless power receiver 450, and information for permitting the chargingof the wireless power receiver 450. The PRU command signal may betransmitted if the wireless power transmitter 400 commands to change thestatus of the wireless power receiver 450, or may be transmitted at apreset cycle of, for example, 250 ms. The wireless power receiver 450changes the configuration according to the PRU command signal, andtransmits a PRU Dynamic signal for reporting the status of the wirelesspower receiver 450 in steps S418 and S419. The PRU Dynamic signaltransmitted by the wireless power receiver 450 may include informationabout at least one of voltage, current, PRU status, and temperature. Theabove status of the wireless power receiver 450 is referred to as an ONstatus S421.

The PRU Dynamic signal may have a data structure as illustrated in Table3.

TABLE 3 Field octets description use units optional fields 1 defineswhich mandatory optional fields are populated Vrect 2 voltage at diodemandatory mV output Irect 2 current at diode mandatory mA output Vout 2voltage at optional mV charge/battery port Iout 2 current at optional mAcharge/battery port temperature 1 temperature of optional Deg C. PRUfrom −40 C. Vrect min dyn 2 Vrect low optional mV limit(dynamic value)Vrect set dyn 2 desired Vrect optional mV (dynamic value) Vrect high dyn2 Vrect high limit optional mV (dynamic value) PRU alert 1 warningsmandatory Bit field RFU(Reserved 3 undefined for Future Use)

The PRU Dynamic signal, as illustrated in Table 3, may include at leastone of information about optional fields, information about a voltage ata rear end of a rectifier of the wireless power receiver Vrect,information about a current at the rear end of the rectifier of thewireless power receiver Irect, information about a voltage at a rear endof a DC/DC converter of the wireless power receiver Vout, informationabout a current at the rear end of the DC/DC converter of the wirelesspower receiver Iout, temperature information, information about theminimum voltage at the rear end of the rectifier of the wireless powerreceiver Vrect min dyn, information about the optimal voltage at therear end of the rectifier of the wireless power receiver Vrect set dyn,information about the maximum voltage at the rear end of the rectifierof the wireless power receiver Vrect high dyn, and alert information PRUalert.

The alert information (‘PRU alert’) may be formed in a data structure asillustrated in Table 4.

TABLE 4 7 6 5 4 3 2 1 0 over over over charge TA transition restart RFUvoltage current temperature complete detect request

The alert information may include, as illustrated in Table 4, ‘overvoltage’ information, ‘over current’ information, ‘over temperature’information, ‘charge complete’ information, ‘TA detect’ information (fordetecting insertion of a wired charging terminal (or Travel Adapter (TA)terminal)), ‘transition’ information (for transition between the SA modeand the NSA mode), ‘restart request’ information and the like.

The wireless power receiver 450 performs charging by receiving a PRUcommand signal. For example, if the wireless power transmitter 400 haspower enough to charge the wireless power receiver 450, the wirelesspower transmitter 400 transmits a PRU command signal for enabling thecharging. The PRU command signal may be transmitted every time thecharging status is changed. The PRU command signal may be transmittedevery 250 ms for example, or may be transmitted when there is a changein parameters. The PRU command signal may be set such that the PRUcommand signal should be transmitted within a preset threshold time(e.g., one second) even though there is no change in a parameter.

The wireless power receiver 450 may detect occurrence of an error. Thewireless power receiver 450 transmits an alert signal to the wirelesspower transmitter 400 in step S420. The alert signal may be transmittedas a PRU Dynamic signal, or may be transmitted as a PRU alert signal.For example, the wireless power receiver 450 may reflect the errorsituations in the PRU alert field in Table 3, and transmit the resultsto the wireless power transmitter 400. Alternatively, the wireless powerreceiver 450 may transmit a single PRU alert signal indicating the errorsituations to the wireless power transmitter 400. Upon receiving thealert signal, the wireless power transmitter 400 enters a latch faultmode in step S422. The wireless power receiver 450 enters a null statusin step S423.

FIG. 5 is a flowchart illustrating operations of a wireless powertransmitter and a wireless power receiver according to anotherembodiment of the present invention. The control method in FIG. 5 willbe described in more detail with reference to FIG. 6. FIG. 6 is a timeaxis graph for power applied by a wireless power transmitter in anembodiment of FIG. 5.

As illustrated in FIG. 5, a wireless power transmitter starts itsdriving in step S501. In addition, the wireless power transmitter resetsan initial configuration (or initial settings) in step S503. Thewireless power transmitter enters the power save mode in step S505. Thepower save mode may correspond to an interval in which the wirelesspower transmitter applies powers having different power levels to itspower transmitting unit. For example, the power save mode may correspondto an interval in which the wireless power transmitter applies seconddetection powers 601 and 602 and third detection powers 611, 612, 613,614 and 615 in FIG. 6, to the power transmitting unit. The wirelesspower transmitter may periodically apply the second powers 601 and 602at a second cycle, and when applying the second powers 601 and 602, thewireless power transmitter may apply the second powers 601 and 602 for asecond period. The wireless power transmitter may periodically apply thethird powers 611, 612, 613, 614 and 615 at a third cycle, and whenapplying the third powers 611, 612, 613, 614 and 615, the wireless powertransmitter may apply the third powers 611, 612, 613, 614 and 615 for athird period. Although a power value for each of the third powers 611,612, 613, 614 and 615 is illustrated as being different from each other,the power value for each of the third powers 611, 612, 613, 614 and 615may be different from, or equal to, each other.

For example after outputting the third power 611, the wireless powertransmitter may output the third power 612 having the same power level.If the wireless power transmitter outputs the third power having thesame power level, the third power may have a power level capable ofdetecting the lowest-power wireless power receiver (e.g., a wirelesspower receiver in category 1, with category 1 denoting the lowest-powerwireless power receiver).

As another example, after outputting the third power 611, the wirelesspower transmitter may output the third power 612 having a differentpower level. If the wireless power transmitter outputs the third powershaving a different power level, each of the third powers may correspondto a power level capable of detecting wireless power receivers incategories 1 to 5. For example, the third power 611 may have a powerlevel capable of detecting a wireless power receiver in category 1, thethird power 612 may have a power level capable of detecting a wirelesspower receiver in category 3, and the third power 613 may have a powerlevel capable of detecting a wireless power receiver in category 5. Forexample, category 1 refers to the lowest-power wireless power receiver,and category 5 refers to the highest-power wireless power receiver.

The second powers 601 and 602 may be the power that can drive thewireless power receiver. More specifically, the second powers 601 and602 may have a power level capable of driving a controller and acommunication unit in the wireless power receiver.

The wireless power transmitter applies the second powers 601 and 602 andthe third powers 611, 612, 613, 614 and 615 to the power receiving unitat a second cycle and a third cycle, respectively. If the wireless powerreceiver is placed on the wireless power transmitter, the impedance seenat one point of the wireless power transmitter may be changed. Thewireless power transmitter detects the change in impedance while thesecond powers 601 and 602 and the third powers 611, 612, 613, 614 and615 are applied. For example, the wireless power transmitter may detecta change in impedance while applying the third power 615. Accordingly,the wireless power transmitter detects an object in step S507. If noobject is detected in step S507, the wireless power transmitter remainsin the power save mode, in which the wireless power transmitterperiodically applies different powers, in step S505.

On the other hand, if an object is detected due to the change inimpedance in step S507, the wireless power transmitter enters the lowpower mode in operation S509. The low power mode is a mode in which thewireless power transmitter applies driving power having a power levelcapable of driving a controller and a communication unit in the wirelesspower receiver. For example, in FIG. 6, the wireless power transmitterapplies driving power 620 to its power transmitting unit. The wirelesspower receiver drives its controller and communication unit by receivingthe driving power 620. The wireless power receiver performscommunication with the wireless power transmitter based on apredetermined scheme using the driving power 620. For example, thewireless power receiver may transmit/receive the data required forauthentication, and based thereon, the wireless power receiver joins thewireless power network managed by the wireless power transmitter.However, if a foreign object other than a wireless power receiver isplaced on the wireless power transmitter, data transmission/receptionwould not be performed therebetween. Accordingly, the wireless powertransmitter determines in step S511 whether the object placed thereon isa foreign object. For example, upon failure to receive a response fromthe object for a preset time, the wireless power transmitter determinesthe object to be a foreign object. If the wireless power transmitterdetermines that the object is not a foreign object in step S511, theobject which is a wireless power receiver, joins the wireless powernetwork managed by the wireless power transmitter in step S519.

If the object is determined to be a foreign object in step S511, thewireless power transmitter enters the latch fault mode in step S513. Forexample, the wireless power transmitter may periodically apply firstpowers 631 to 634 in FIG. 6 at a first cycle. The wireless powertransmitter may detect a change in impedance while applying the firstpowers. For example, if the foreign object is removed, the wirelesspower transmitter may detect a change in impedance, and the wirelesspower transmitter determines that the foreign object is removed. If theforeign object is not removed, the wireless power transmitter may notdetect a change in impedance, and the wireless power transmitterdetermines that the foreign object is not removed. If the foreign objectis not removed, the wireless power transmitter may output at least oneof lamp light and alert tone, notifying the user that the current statusof the wireless power transmitter is an error status. Accordingly, thewireless power transmitter may include an output unit for outputting atleast one of the lamp light and the alert tone.

If it is determined that the foreign object has not been removed in stepS515, the wireless power transmitter remains in the latch fault mode instep S513. On the other hand, if it is determined that the foreignobject has been removed in step S515, the wireless power transmitterre-enters the power save mode in step S517. For example, the wirelesspower transmitter applies second powers 651 and 652 and third powers 661to 665 in FIG. 6.

As described above, the wireless power transmitter enters the latchfault mode, if a foreign object other than the wireless power receiveris placed thereon. In addition, the wireless power transmitter maydetermine whether the foreign object is removed, depending on the changein impedance, which is caused by the power applied in the latch faultmode. In other words, a latch fault mode entry condition in theembodiments of FIGS. 5 and 6 is the arrangement of the foreign object.The wireless power transmitter may have a variety of latch fault modeentry conditions in addition to the arrangement of the foreign object.For example, the wireless power transmitter may enter the latch faultmode if the wireless power transmitter is cross-connected to thewireless power receiver placed thereon.

Accordingly, upon occurrence of cross connection, the wireless powertransmitter is required to return to the initial status, and removal ofthe wireless power receiver is required. The wireless power transmittermay set, as a latch fault mode entry condition, cross connection, whichoccurs if a wireless power receiver placed on another wireless powertransmitter joins the wireless power network managed by the wirelesspower transmitter. Reference will be made to FIG. 7, to describe anoperation of a wireless power transmitter, which is performed when anerror including cross connection occurs.

FIG. 7 is a flowchart illustrating a control method of a wireless powertransmitter according to an embodiment of the present invention. Thecontrol method in FIG. 7 will be described in more detail with referenceto FIG. 8. FIG. 8 is a time axis graph for power applied by a wirelesspower transmitter in an embodiment of FIG. 7. As illustrated in FIG. 7,a wireless power transmitter starts its driving in step S701.

In addition, the wireless power transmitter resets an initialconfiguration (or initial settings) in step S703. The wireless powertransmitter enters the power save mode in step S705. The power save modemay correspond to an interval in which the wireless power transmitterapplies powers having different power levels to its power transmittingunit. For example, the power save mode may correspond to an interval inwhich the wireless power transmitter applies second powers 801 and 802and third powers 811, 812, 813, 814 and 815 in FIG. 8, to the powertransmitting unit. The wireless power transmitter may periodically applythe second powers 801 and 802 at a second cycle, and when applying thesecond powers 801 and 802, the wireless power transmitter may apply thesecond powers 801 and 802 for a second period. The wireless powertransmitter may periodically apply the third powers 811, 812, 813, 814and 815 at a third cycle, and when applying the third powers 811, 812,813, 814 and 815, the wireless power transmitter may apply the thirdpowers 811, 812, 813, 814 and 815 for a third period. Although a powervalue for each of the third powers 811, 812, 813, 814 and 815 isillustrated as being different from each other, the power value for eachof the third powers 811, 812, 813, 814 and 815 may be different from, orequal to, each other.

The second powers 801 and 802 may be the power that can drive thewireless power receiver. More specifically, the second powers 801 and802 may have a power level capable of driving a controller and acommunication unit in the wireless power receiver.

The wireless power transmitter applies the second powers 801 and 802 andthe third powers 811, 812, 813, 814 and 815 to the power receiving unitat a second cycle and a third cycle, respectively. If the wireless powerreceiver is placed on the wireless power transmitter, the impedance seenat one point of the wireless power transmitter may be changed. Thewireless power transmitter may detect the change in impedance while thesecond powers 801 and 802 and the third powers 811, 812, 813, 814 and815 are applied. For example, the wireless power transmitter may detecta change in impedance while applying the third power 815. Accordingly,the wireless power transmitter detects an object in step S707. If noobject is detected in step S707, the wireless power transmitter remainsin the power save mode, in which the wireless power transmitterperiodically applies different powers, in step S705.

On the other hand, if an object is detected due to the change inimpedance in step S707, the wireless power transmitter enters the lowpower mode in step S709. The low power mode is a mode in which thewireless power transmitter applies driving power having a power levelcapable of driving a controller and a communication unit in the wirelesspower receiver. For example, in FIG. 8, the wireless power transmitterapplies driving power 820 to its power transmitting unit. The wirelesspower receiver drives its controller and communication unit by receivingthe driving power 820. The wireless power receiver performscommunication with the wireless power transmitter based on apredetermined scheme using the driving power 820. For example, thewireless power receiver may transmit/receive the data required forauthentication, and based thereon, the wireless power receiver may jointhe wireless power network managed by the wireless power transmitter.

Thereafter, the wireless power transmitter enters the power transfermode, in which the wireless power transmitter transmits charging power,in step S711. For example, the wireless power transmitter may applycharging power 821 as in FIG. 8, and the charging power may betransmitted to the wireless power receiver.

In the power transfer mode, the wireless power transmitter determines instep S713 whether an error occurs. Herein, the error may include aforeign object being placed on a wireless power transmitter, crossconnection, over voltage, over current, over temperature, and the like.The wireless power transmitter may include a sensing unit capable ofmeasuring the over voltage, over current, over temperature, and thelike. For example, the wireless power transmitter may measure a power ora current at a reference point, and if the measured voltage or currentexceeds a threshold, the wireless power transmitter determines thatover-voltage or over-current conditions are met. The wireless powertransmitter may include a temperature sensing means, and the temperaturesensing means may measure the temperature at a reference point of thewireless power transmitter. If the temperature at the reference pointexceeds a threshold, the wireless power transmitter determines that theover-temperature conditions are met.

Although an error, which occurs when a foreign object is additionallyplaced on the wireless power transmitter, is illustrated in theembodiment of FIG. 8, the error is not limited thereto, and it will beapparent to those of ordinary skill in the art that the wireless powertransmitter may operate in a similar process, even upon occurrence of aforeign object being placed on the wireless power transmitter, crossconnection, over voltage, over current, over temperature, and the like.

If no error occurs in step S713, the wireless power transmitter remainsin the power transfer mode in step S711. On the other hand, if an erroroccurs in step S713, the wireless power transmitter enters the latchfault mode in step S715. For example, the wireless power transmitter mayapply first powers 831 to 835 as in FIG. 8. In addition, the wirelesspower transmitter may output an error indication including at least oneof lamp light and alert tone during the latch fault mode. If it isdetermined in step S717 that a foreign object or a wireless powerreceiver has not been removed, the wireless power transmitter remains inthe latch fault mode in step S715. On the contrary, if it is determinedin step S717 that a foreign object or a wireless power receiver has beenremoved, the wireless power transmitter re-enters the power save mode instep S719. For example, the wireless power transmitter may apply seconddetection powers 851 and 852 and third detection powers 861 to 865 inFIG. 8.

So far, a description has been made of an operation performed when anerror occurs while the wireless power transmitter transmits chargingpower. A description will now be made of an operation performed when aplurality of wireless power receives on a wireless power transmitterreceive charging power.

FIG. 9 is a flowchart illustrating a control method of a wireless powertransmitter according to an embodiment of the present invention. Thecontrol method in FIG. 9 will be described in more detail with referenceto FIG. 10. FIG. 10 is a time axis graph for power applied by a wirelesspower transmitter in an embodiment of FIG. 9.

As illustrated in FIG. 9, a wireless power transmitter transmitscharging power to a first wireless power receiver in step S901. Inaddition, the wireless power transmitter may cause a second wirelesspower receiver to join the wireless power network in step S903. Thewireless power transmitter also transmits charging power to the secondwireless power receiver in step S905. More specifically, the wirelesspower transmitter may apply, to the power receiving units, a sum of thecharging power required by the first wireless power receiver and thecharging power required by the second wireless power receiver.

An example of steps S901 to S905 is illustrated in FIG. 10. For example,the wireless power transmitter remains in the power save mode in whichthe wireless power transmitter applies second powers 1001 and 1002 andthird powers 1011 to 1015. Thereafter, upon detecting the first wirelesspower receiver, the wireless power transmitter enters the low power modein which the wireless power transmitter keeps detection power 1020.Thereafter, the wireless power transmitter enters the power transfermode in which the wireless power transmitter applies first chargingpower 1030. The wireless power transmitter detects the second wirelesspower receiver, and causes the second wireless power receiver to jointhe wireless power network. In addition, the wireless power transmittermay apply second charging power 1040 that has the total power levelcorresponding to a power level required by the first wireless powerreceiver and a power level required by the second wireless powerreceiver.

Referring back to FIG. 9, the wireless power transmitter detects whetheran error has occurred in step S907 while transmitting the charging powerto both of the first and second wireless power receivers in step S905.As described above, the error may include arrangement of a foreignobject, cross connection, over voltage, over current, over temperature,and the like. If no error occurs in step S907, the wireless powertransmitter continues to apply the second charging power 1040.

On the other hand, if an error occurs in step S907, the wireless powertransmitter enters the latch fault mode in step S909. For example, thewireless power transmitter may apply first powers 1051 to 1055 in FIG.10 at a first cycle. The wireless power transmitter determines inoperation S911 whether both of the first wireless power receiver and thesecond wireless power receiver have been removed. For example, thewireless power transmitter may detect a change in impedance whileapplying the first powers 1051 to 1055. Based on whether the impedancereturns to its initial value, the wireless power transmitter maydetermine whether both of the first wireless power receiver and thesecond wireless power receiver are removed.

If it is determined that both of the first wireless power receiver andthe second wireless power receiver have been removed in step S911, thewireless power transmitter enters the power save mode in step S913. Forexample, the wireless power transmitter may apply second powers 1061 and1062 and third powers 1071 to 1075 in FIG. 10 at a second cycle and athird cycle, respectively.

As described above, even when applying charging power to a plurality ofwireless power receivers, the wireless power transmitter may easilydetermine whether a wireless power receiver or a foreign object isremoved, upon occurrence of an error.

FIG. 11 is a block diagram of a wireless power transmitter and awireless power receiver according to an embodiment of the presentinvention.

A wireless power transmitter 1100 includes a communication unit 1110, aPower Amplifier (PA) 1120 and a resonator 1130. A wireless powerreceiver 1150 includes a communication unit 1151, an ApplicationProcessor (AP) 1152, a Power Management Integrated Circuit (PMIC) 1153,a wireless power integrated circuit 1154, a resonator 1155, an InterfacePower Management IC (IFPM) 1157, a wired charging adapter (also known asa Travel Adapter (TA)) 1158, and a battery 1159.

The communication unit 1110 performs communication with thecommunication unit 1151 based on a predetermined scheme (e.g., BLEscheme). For example, the communication unit 1151 in the wireless powerreceiver 1150 may transmit a PRU Dynamic signal having the datastructure of Table 3 to the communication unit 1110 in the wirelesspower transmitter 1100. As described above, the PRU Dynamic signal mayinclude at least one of voltage information, current information,temperature information and alert information of the wireless powerreceiver 1150.

Based on the received PRU Dynamic signal, an output power value from thepower amplifier 1120 may be adjusted. For example, if over voltage, overcurrent or over temperature is applied to the wireless power receiver1150, a power value output from the power amplifier 1120 may be reduced.In addition, if the voltage or current of the wireless power receiver1150 is less than a preset value, the power value output from the poweramplifier 1120 may increase.

The charging power from the resonator 1130 is wirelessly transmitted tothe resonator 1155.

The wireless power integrated circuit 1154 rectifies the charging powerreceived from the resonator 1155, and performs DC/DC conversion on therectified charging power. The wireless power integrated circuit 1154 maydrive the communication unit 1151 with the converted power, or maycharge the battery 1159 with the converted power.

A wired charging terminal may be inserted in the wired charging adapter(TA) 1158. In the wired charging adapter 1158, a wired charging terminalsuch as a 30-pin connector, a Universal Serial Bus (USB) connector orthe like may be inserted. The wired charging adapter 1158 may receivepower supplied from an external power source, and charge the battery1159 with the received power.

The interface power management integrated circuit 1157 processes thepower received from the wired charging terminal, and outputs theprocessed power to the battery 1159 and the power management integratedcircuit 1153.

The power management integrated circuit 1153 manages the power receivedwirelessly or by wires, and the power applied to each of the componentsof the wireless power receiver 1150. The AP 1152 receives powerinformation from the power management integrated circuit 1153, andcontrols the communication unit 1151 to transmit a PRU Dynamic signalfor reporting the received power information.

A node 1156 connected to the wireless power integrated circuit 1154 mayalso be connected to the wired charging adapter 1158. If a wiredcharging connector (or a wired charging terminal) is inserted in thewired charging adapter 1158, a preset voltage (e.g., 5V) may be appliedto the node 1156. The wireless power integrated circuit 1154 monitors avoltage applied to the node 1156, to determine whether the wiredcharging adapter 1158 is inserted.

FIG. 12A is a flowchart illustrating a control method of a wirelesspower receiver according to an embodiment of the present invention.

Referring to FIG. 12A, the wireless power receiver 1150 wirelesslyreceives charging power from the wireless power transmitter 1100 in stepS1201. The wireless power receiver 1150 determines in step S1203 whethera wired charging terminal is inserted in a wired charging adapter (TA).For example, the wireless power receiver 1150 may determine whether thewired charging terminal is inserted in the wired charging adapter, bydetermining whether a voltage applied to a rear end of the wiredcharging adapter corresponds to a preset voltage value.

If it is determined that the wired charging terminal is inserted in stepS1203, the wireless power receiver 1150 transmits a signal indicatingthe insertion of the wired charging terminal, to the wireless powertransmitter 1100 in step S1205. For example, the wireless power receiver1150 may transmit, to the wireless power transmitter 1100, a PRU Dynamicsignal indicating TA detect (3) in a PRU alert field in Table 4. Thewireless power receiver 1150 transmits a signal indicating the insertionof the wired charging terminal to the wireless power transmitter 1100 asa signal different from the PRU Dynamic signal. The wireless powerreceiver 1150 stops wireless charging by releasing the connection to theresonator 1155.

FIG. 12B is a flowchart illustrating a control method of a wirelesspower transmitter according to an embodiment of the present invention.

Referring to FIG. 12B, the wireless power transmitter 1100 wirelesslytransmits charging power to the wireless power receiver 1150 in stepS1211. The wireless power transmitter 1100 receives a signal indicatingthe insertion of the wired charging terminal from the wireless powerreceiver 1150 in step S1213. If the signal indicating the insertion ofthe wired charging terminal is received in step S1213, the wirelesspower transmitter 1100 adjusts the charging power in step S1215. Forexample, the wireless power transmitter 1100 may stop the transmissionof the charging power by adjusting the charging power to zero (0).

As described above, if the wireless power receiver 1150 performs wiredcharging, the wireless power transmitter 1100 stops the wirelesscharging, preventing overpower from being applied.

FIG. 13 is a flowchart illustrating operations of a wireless powertransmitter and a wireless power receiver according to an embodiment ofthe present invention.

Referring to FIG. 13, the wireless power transmitter 1100 transmits acharging start command signal to the wireless power receiver 1150 instep S1301. In response thereto, the wireless power receiver 1150performs wireless charging by turning on a load switch in step S1302.The wireless power receiver 1150 transmits a PRU Dynamic signal in stepS1303, and the wireless power transmitter 1100 receives and analyzes thePRU Dynamic signal in step S1304. Accordingly, the wireless powertransmitter 1100 may determine information about voltage, current andtemperature of the wireless power receiver 1150, or wireless chargingenvironment change information such as information about insertion ofthe wired charging terminal.

A user may insert the wired charging terminal in the wireless powerreceiver 1150, and the wireless power receiver 1150 detects theinsertion in step S1305. The wireless power receiver 1150 determines instep S1306 whether wired or wireless power is received. If neither ofthe wired nor wireless power is received in step S1306, the wirelesspower receiver 1150 enters the power save mode in step S1307. However,if it is determined that both of wired charging and wireless chargingare performed in step S1306, the IFPM 1157 in the wireless powerreceiver 1150 stops the wireless charging by releasing the connectionfrom the resonator 1155 in step S1308.

The wireless power receiver 1150 outputs information indicating thedetection of the insertion of the wired charging terminal to thecommunication unit 1151 in step S1309, and the communication unit 1151transmits a signal indicating the detection of the insertion of thewired charging terminal to the wireless power transmitter 1100 in stepS1310. In response thereto, the wireless power transmitter 1100 adjuststhe charging power in step S1311. For example, the wireless powertransmitter 1100 may stop the wireless charging by adjusting thecharging power to zero (0).

The wireless power transmitter 1100 instructs ‘no power reception’ instep S1312, and the wireless power transmitter 1100 transmits a loadswitch OFF signal to the wireless power receiver 1150 in step S1313.Upon receiving the load switch OFF signal, the wireless power receiver1150 may turns off the load switch in step S1314.

Even after that, the wireless power receiver 1150 may periodicallytransmit a PRU Dynamic signal in step S1315. The wireless powertransmitter 1100 receives and analyzes the PRU Dynamic signal in stepS1316.

The wireless power receiver 1150 detects the release (or plug-out) ofthe wired charging terminal (TA) in step S1317. For example, thewireless power receiver 1150 may detect the release of the wiredcharging terminal by detecting a change in voltage applied to a rear endof the wired charging adapter 1158. The wireless power receiver 1150transmits a signal indicating the detection of the release of the wiredcharging terminal to the wireless power transmitter 1100 in step S1318.For example, the wireless power receiver 1150 may transmit the signalindicating the detection of the release of the wired charging terminalas a PRU Dynamic signal or a single signal. The wireless powertransmitter 1100 analyzes the PRU Dynamic signal or the single signaland determines that the insertion of the wired charging terminal intothe wireless power receiver 1150 is released, in step S1319.

The wireless power transmitter 1100 transmits a load switch ON signal tothe wireless power receiver 1150 in step S1320, and upon receiving theload switch ON signal, the wireless power receiver 1150 turns on theload switch in step S1321. The wireless power transmitter 1100 performswireless charging by re-adjusting the charging power, and the wirelesspower receiver 1150 performs wireless charging by turning on the loadswitch.

As described above, the wireless power transmitter 1100 may determinewhether the wired charging terminal is inserted in, or drawn out fromthe wireless power receiver 1150. The wireless power transmitter 1100may adjust the charging power depending on whether the wired chargingterminal is inserted in, or drawn out from the wireless power receiver1150, thereby preventing the waste of power and preventing overpowerfrom being applied to the wireless power receiver 1150.

FIG. 14 is a block diagram of a communication unit and peripheralcomponents of a wireless power receiver according to an embodiment ofthe present invention.

As illustrated in FIG. 14, the communication unit 1151 of the wirelesspower receiver 1150 includes a Random Access Memory (RAM) 1161, and aRead Only Memory (ROM) 1162. The communication unit 1151 performscommunication with the wireless power transmitter 1100 based on apredetermined scheme (e.g., BLE scheme). Accordingly, a stack (e.g., BLEstack) of the predetermined communication scheme needs to be loaded inthe RAM 1161 of the communication unit 1151. The communication unit 1151may receive a BLE stack from the AP 1152, and load the BLE stack in theRAM 1161. As such, a mode in which the communication unit 1151 receivesa stack of a predetermined communication scheme from the AP 1152 andloads the stack in the RAM 1161 is referred to as a Non-Stand Alone(NSA) mode.

The wireless power receiver 1150 is placed on the wireless powertransmitter 1100 after the battery 1159 is discharged. In this case, thewireless power receiver 1150 cannot drive the AP 1152 since the battery1159 is discharged.

The wireless power receiver 1150 drives the communication unit 1151 ofthe wireless power receiver 1150 by receiving detection-purpose powerbeacons. However, since the AP 1152 cannot be driven as stated above,the communication unit 1151 may not receive the stack of thepredetermined communication scheme from the AP 1152. The communicationunit 1151 may store the stack of the predetermined communication schemein the ROM 1162, and performs communication with the wireless powertransmitter 1100 using the stack of the predetermined communicationscheme, which is stored in the ROM 1162. As described above, a mode inwhich the communication unit 1151 performs communication using the stackof the predetermined communication scheme, which is stored in the ROM1162, is referred to as a Stand Alone (SA) mode.

FIG. 15A is a flowchart illustrating a control method of a wirelesspower receiver according to an embodiment of the present invention.

Referring to FIG. 15A, the wireless power receiver 1150 is powered offdue to the discharge of the battery 1159 in step S1501. The wirelesspower receiver 1150 receives first power capable of driving thecommunication unit 1151, from the wireless power transmitter 1100 instep S1503, and drives the communication unit 1151 using the receivedpower. The wireless power receiver 1150 enters the SA mode, and loads aBLE stack for example, from the ROM in step S1505. The communicationunit 1151 of the wireless power receiver 1150 performs communicationwith the wireless power transmitter 1100 using the loaded BLE stack instep S1507.

FIG. 15B is a flowchart illustrating a control method of a wirelesspower receiver according to an embodiment of the present invention.

Referring to FIG. 15B, the wireless power receiver 1150 performswireless charging while operating in the SA mode. Based on the wirelesscharging, the wireless power receiver 1150 turns on the battery 1159 andthe AP 1152 in step S1511. The wireless power receiver 1150 transitionsfrom the SA mode to the NSA mode in step S1513. The wireless powerreceiver 1150 transmits a mode transition detection signal to thewireless power transmitter 1100 in step S1515. The wireless powerreceiver 1150 loads a BLE stack from the AP 1152 in step S1517, andresumes the communication with the wireless power transmitter 1100 instep S1519.

FIG. 15C is a flowchart illustrating a control method of a wirelesspower transmitter according to an embodiment of the present invention.

Referring to FIG. 15C, the wireless power transmitter 1100 transmitscharging power to the wireless power receiver 1150 in step S1521. Thewireless power transmitter 1100 receives a detection signal indicatingtransition from the SA mode to the NSA mode from the wireless powerreceiver 1150 in step S1523. The wireless power transmitter 1100 waitsfor a preset waiting time in step S1525. For example, the wireless powertransmitter 1100 may be set to exclude the wireless power receiver 1150from the wireless power network if no signal is received from thewireless power receiver 1150 for one second. However, if a detectionsignal indicating transition from the SA mode to the NSA mode isreceived from the wireless power receiver 1150, the wireless powertransmitter 1100 does not exclude the wireless power receiver 1150 fromthe wireless power network even if no signal is received from thewireless power receiver 1150 for a preset waiting time.

If the preset waiting time has elapsed, the wireless power transmitter1100 resumes communication with the wireless power receiver 1150 in stepS1527.

As described above, if the wireless power receiver 1150 transitions fromthe SA mode to the NSA mode, its communication with the wireless powertransmitter 1100 may be cut off for a predetermined time. However, byreceiving a transition signal from the SA mode to the NSA mode from thewireless power receiver 1150, the wireless power transmitter 1100 doesnot exclude the wireless power receiver 1150 from the wireless powernetwork, even if no signal is received from the wireless power receiver1150 for a preset waiting time. As a result, it is possible to preventan error from unintentionally occurring due to the mode transition ofthe wireless power receiver.

As described above, the wireless power transmitter 1100 may determinechanges in wireless power transmission environment, such as the modetransition, and does not exclude the wireless power receiver 1150 fromthe wireless power network in response to the changes in wireless powertransmission environment.

FIG. 16 is a block diagram of a wireless power receiver according to anembodiment of the present invention. As illustrated in FIG. 16, anapplication processor 1621 of a wireless power receiver 1600 includes amemory 1622. In addition, a communication unit 1611 also individuallyincludes a BLE memory 1615. The memory 1622 of the application processor1621 may store a public address for communication of the wireless powerreceiver 1600. In addition, the BLE memory 1615 may store a stack (e.g.,BLE stack) for communication. More specifically, the BLE memory 1615 mayalso store the public address.

The wireless power receiver 1600 may use addresses defined in Table 5below, in each of the SA mode and the NSA mode.

TABLE 5 Address in SA mode Address in NSA mode Random address Randomaddress same as that in SA mode Random address Public address Publicaddress Public address First random address Second random address

Each situation in Table 5 will be described in more detail below.

1. Way to Keep Using Random Address

The wireless power receiver 1600 performs communication with thewireless power transmitter 1100 using a random address in the SA mode.The random address may be generated by the wireless power receiver 1600.

The wireless power receiver 1600, as described above, transmits a modetransition detection signal to the wireless power transmitter 1100. Inthis case, the wireless power receiver 1600 may store the random addressit has used in the SA mode, while transmitting the mode transitiondetection signal.

The wireless power transmitter 1100 receives the mode transitiondetection signal, and stores the random address it has used in the SAmode.

The wireless power receiver 1600 transitions to the NSA mode, and mayuse the same random address it has used in the SA mode, even in the NSAmode. The wireless power transmitter 1100 may also use the same randomaddress it has used in the SA mode. Accordingly, the wireless powertransmitter 1100 and the wireless power receiver 1600 performcommunication using the random address they have used in the SA mode,even in the NSA mode. Upon transition of the mode, the wireless powertransmitter 1100 keeps applying the charging power, and does notdetermine the wireless power receiver 1600 to be a foreign object evenif no signal is received from the wireless power receiver 1600 for apreset time.

2. Way to Change Random Address to Public Address

The wireless power receiver 1600 performs communication with thewireless power transmitter 1100 using a random address in the SA mode.

When transitioning from the SA mode to the NSA mode, the wireless powerreceiver 1600 obtains a public address from the application processor1621 and stores the public address in the RAM. The wireless powerreceiver 1600 transmits a mode transition detection signal to thewireless power transmitter 1100. The mode transition detection signalmay include public address information. The wireless power transmitter1100 checks information about the public address to be used in the NSAmode, by analyzing the received mode transition detection signal.

The wireless power receiver 1600 performs mode transition from the SAmode to the NSA mode. In addition, the wireless power receiver 1600performs communication with the wireless power transmitter 1100 usingthe public address. The wireless power transmitter 1100 may also performcommunication with the wireless power receiver 1600 using the publicaddress obtained from the mode transition detection signal. Upontransition of the mode, the wireless power transmitter 1100 keepsapplying the charging power, and does not determine the wireless powerreceiver 1600 to be a foreign object even if no signal is received fromthe wireless power receiver 1600 for a preset time.

3. Way to Keep Using Public Address

The wireless power receiver 1600 may store in advance the same publicaddress as that of the application processor 1621 in the ROM of thecommunication unit 1611. Accordingly, the wireless power receiver 1600performs communication with the wireless power transmitter 1100 usingthe public address even in the SA mode. The wireless power receiver 1600transmits a mode transition detection signal to the wireless powertransmitter 1100 before the mode transition.

The wireless power transmitter 1100 stores the public address of thewireless power receiver 1600. In addition, the wireless powertransmitter 1100 receives the mode transition detection signal, and usesthe stored public address when resuming the communication in the NSAmode. Upon transition of the mode, the wireless power transmitter 1100keeps applying the charging power, and does not determine the wirelesspower receiver 1600 to be a foreign object even if no signal is receivedfrom the wireless power receiver 1600 for a preset time.

4. Way to Change First Random Address to Second Random Address

The wireless power receiver 1600 generates a first random address, andperforms communication with the wireless power transmitter 1100 usingthe generated first random address. The wireless power receiver 1600transitions from the SA mode to the NSA mode. The wireless powerreceiver 1600 transmits a mode transition detection signal to thewireless power transmitter 1100.

Upon transition of the mode, the wireless power transmitter 1100 keepsapplying the charging power, and does not determine the wireless powerreceiver 1600 to be a foreign object even if no signal is received fromthe wireless power receiver 1600 for a preset time.

The wireless power receiver 1600 generates a second random address inthe NSA mode. The wireless power receiver 1600 may re-perform the bootoperation (step S407) in FIG. 4, using the second random address. Morespecifically, the wireless power receiver 1600 may perform the processof transmitting a PTU searching signal (step S410), receiving PRUresponse signal (step S411), transmitting PRU static signal (step S412),and receiving a PTU static signal (step S413), by using the secondrandom address.

As is apparent from the foregoing description, various embodiments ofthe present invention may provide a wireless power receiver capable ofperforming communication with a wireless power transmitter even duringdischarge of its battery, and a control method thereof. In addition,various embodiments of the present invention may provide a wirelesspower transmitter for performing communication in response to thebattery discharge, and a control method thereof. Moreover, the wirelesspower transmitter and the wireless power receiver may stably maintaincommunication even in a mode transition process, so communication forwireless charging may be stably performed.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims and their equivalents.

What is claimed is:
 1. A control method for performing wireless chargingin a wireless power receiver, the control method comprising: receivingcharging power from a wireless power transmitter; detecting transitionof the wireless power receiver from a Stand Alone (SA) mode to a NonStand Alone (NSA) mode; upon detecting the mode transition, generating amessage including address information used to re-connect with thewireless power transmitter; and transmitting the message to the wirelesspower transmitter.
 2. The control method of claim 1, wherein the messageincludes a Power Reception Unit (PRU) alert signal.
 3. The controlmethod of claim 1, further comprising: upon detecting the modetransition, storing the address information used to re-connect with thewireless power transmitter.
 4. The control method of claim 1, furthercomprising: upon completion of the mode transition, re-connecting withthe wireless power transmitter using the address information.
 5. Thecontrol method of claim 4, further comprising: upon completion of themode transition, loading a communication scheme stack for communicationwith the wireless power transmitter from an application processor of thewireless power receiver; and re-connecting with the wireless powertransmitter using the address information, based on the loadedcommunication scheme stack.
 6. The control method of claim 5, whereinthe address information used to re-connect with the wireless powertransmitter includes a public address that is different from a randomaddress in the SA mode.
 7. The control method of claim 1, wherein theaddress information used to re-connect with the wireless powertransmitter includes a public address that is the same as a publicaddress in the SA mode.
 8. The control method of claim 1, wherein theaddress information used to re-connect with the wireless powertransmitter includes a random address that is the same as a randomaddress in the SA mode.
 9. The control method of claim 1, wherein theaddress information used to re-connect with the wireless powertransmitter includes a second random address that is different from afirst random address in the SA mode.
 10. A control method for performingwireless charging in a wireless power transmitter, the control methodcomprising: transmitting charging power to a wireless power receiver;receiving, from the wireless power receiver, a message including addressinformation used to re-connect with the wireless power transmitter; andupon receiving the message from the wireless power receiver,reconnecting with the wireless power receiver using the addressinformation.
 11. The control method of claim 10, further comprisingstoring the address information to be used to re-connect with thewireless power transmitter.
 12. The control method of claim 10, whereinthe address information used to re-connect with the wireless powertransmitter includes a public address that is different from a randomaddress in a Stand Alone (SA) mode of the wireless power receiver. 13.The control method of claim 10, wherein the address information used tore-connect with the wireless power transmitter includes a public addressthat is the same as a public address in an SA mode of the wireless powerreceiver.
 14. The control method of claim 10, wherein the addressinformation used to re-connect with the wireless power transmitterincludes a random address that is the same as a random address in an SAmode of the wireless power receiver.
 15. The control method of claim 10,wherein the address information used to re-connect with the wirelesspower transmitter includes a second random address that is differentfrom a first random address in an SA mode of the wireless powerreceiver.